Pigment Yellow 180 is a benzimidazolone pigment which is widely used in the fields of printing ink, plastics, dope dyeing of polypropylene etc., toner, and the like.
However as Pigment Yellow 180 has insufficient transparency in spite of having the advantages of high heat resistant property and of having no chlorine in its structure, the condensation azo pigment and isoindolinone pigment which are yellow pigment having the same color region as Pigment Yellow 180 are often used in the field of color filter where a higher transparency is required.
Further, as Pigment Yellow 180 so far applied is hydrophilic, it could not be applied in the field where the hydrophobic property is desired.
Pigment Yellow 180 is disclosed in Japanese Examined Patent Publication No. Hei 2-37949. It describes that Pigment Yellow 180 is suitable for coloring organic polymer materials such as polyolefins like polypropylene, etc., and polyvinyl chloride. And yellow toner using Pigment Yellow 180 and its production method are disclosed in Japanese Laid-open Patent Publication Nos. Hei 6-230607 and Hei 6-266163. However in these publications there is no description on the means improving a transparency and the applications utilizing it.
On the other hand the method of improving a transparency of Pigment Yellow 180 by conducting azo-coupling at low temperature and in relatively short time and the method of using the pigment obtained thereby as a pigment for an electrophotographic toner and developer are disclosed in Japanese Laid-open Patent Publication No. Hei 8-209017.
However the transparency which is achieved by the method described in Japanese laid-open Patent Publication No. Hei 8-209017 is not one that is satisfied completely and further improvement is desired. Furthermore there is no description of the means therein to increase the hydrophobic property of Pigment Yellow 180.
Considering the above situation, the present invention has a purpose to offer Pigment Yellow 180 with a high transparency required for a color filter provided for liquid crystal display equipment and for a color toner provided for a copying machine and a printing machine, and the production method thereof.
Further the present invention has a purpose to offer Pigment Yellow 180 with the above transparency and a high hydrophobic property in the same time and the production method thereof.
Furthermore the present invention has a purpose to offer a various kind of materials containing above-described Pigment Yellow 180 as a colorant.
After being dedicated to research and examine, the present inventors have found that Pigment Yellow 180 with a high transparency and a small particle size can be produced by conducting a preparation of a coupling component at relatively low temperature and slowly in the production process of said pigment to prevent coagulation of the pigment and furthermore Pigment Yellow 180 with high hydrophobic property in addition to a high transparency can be produced by treating a surface of the above-described pigment.
Therefore the present invention relates to Pigment Yellow 180 represented by the following formula and the production method thereof, which is improved the transparency by xe2x88x922 or less of dL value which is obtained by comparing the brightness measured by a spectrophotometer with that of the control product. 
The above described limit of dL value which corresponds to a scale of transparency is determined by deducting L value which is measured of the control product that is PV Fast Yellow HG or Novoperm Yellow P-HG (Both are the pigments which belong to Pigment Yellow 180.) which are the commercial products and are supplied by Clariant Japan K.K. by the testing method in the Comparative Examples 1 to 3 described below, from L value which is measured of Pigment Yellow 180 that is produced by the way described in the present invention by the same testing method as described above. As described in the Comparative Example 1 later, the higher the absolute value of dL value is, the larger the difference of transparency is and the dL value of Pigment Yellow 180 according to the present invention is usually xe2x88x922 or less and one with particularly high transparency is xe2x88x923 or less.
The production method for Pigment Yellow 180 having improved transparency according to the present invention is characterized in that 1,2-bis(2-aminophenoxy)ethane is diazotized with sodium nitrite and a fine slurry of 5-acetoacetylamino-benzimidazolone is used as a coupling component when the generated product by diazotization reaction is made a coupling with 5-acetoacetylamino-benzimidazolone in accordance with the publicly known methods such as the methods described in Japanese Examined Patent Publication No. Hei 2-37949 or Japanese Laid-open Patent Publication No. Hei 8-209017, for example.
The fine slurry can be prepared, when preparing a slurry of 5-acetoacetylamino-benzimidazolone, for example, by adding an organic acid such as acetic acid, by adding such organic acid at lower temperature such as 10xc2x0 C. or below and more slowly such as taking 5 minutes to 1 hour, preferably 15 minutes or longer than so far applied.
It means that the particle size of the slurry expressed by xe2x80x9cfinexe2x80x9d shows the comparable degree of fineness with the particle size of the slurry obtained by the above method raised as an example not depending on the means actually taken and that it has finer particle size than that which is prepared by the ordinary method wherein the addition of an organic acid is conducted at higher temperature than the slurry preparation condition described above and at the ordinary adding speed. And at this moment a nonionic surfactant can be added such as dimethylcocoalkylamine oxide which is described in the example of Japanese Laid-open patent Publication No. Hei 8-209017, polyglycol ether of aliphatic alcohol or phosphoric ester. By this the stabilization of a particle and a flowability of slurry are provided. On the other hand since a transparency and a hydrophobic property are prevented by addition of such surfactants, it is preferred to add no surfactant or not so much, for example 6 weight parts or less, if added, relative to the weight of benzimidazolone.
To be surprised, by preparing such fine slurry and by using it as a coupling component, a high transparency can be given to Pigment Yellow 180 having L value of usually 50 or less based on the measured values described in the Comparative Example 1 wherein a polyvinyl chloride compound is used as a resin, preferably 48 or less, further preferably 46 to 40, which has not been achieved by the prior art as shown in the Examples or Comparative Examples below.
This invention further relates to Pigment Yellow 180, to which such a high hydrophobic property is given as the sedimentation time in hydrophobic property test by sedimentation method in water takes 1 hour or more in addition to the above transparency and a production method thereof.
This sedimentation time which is a scale of hydrophobic property is determined by the method which is described in the Comparative Example 5 below.
Such high hydrophobic property can be achieved by surface treatment of a pigment using a wax. This surface treatment is conducted generally either by the method wherein the synthesized pigment is mixed with wax emulsion continuously, and then the emulsion is destructed by heat to coat on the surface of aforementioned pigment with the wax, or by the method wherein after the above described coupling reaction is completed, it is dispersed in slurry form by adding water and organic solvent such like isobutanol thereto in an autoclave, and then mixed with wax emulsion and the emulsion is destructed by heat to coat on the surface of aforementioned pigment with the wax.
The waxes used for the above described surface treatment may not be limited to their kind if emulsification is possible, however for instance fatty acid and fatty acid ester type of waxes such as a montan wax and a carnauba wax with drop point 70-165xc2x0 C., amide waxes such as ethylene-bis-stearyl amide, fatty acid monoamide, olefinic waxes such as polyethylene, oxidized polyethylene, polypropylene, oxidized polypropylene can be exemplified. Preferably a montan wax, ethylene-bis-stearyl amide and an oxidized polypropylene wax are used.
The emulsions of waxes raised above are commercially available and they can be used as they are. A preparation of wax emulsion can be made as follows, for example.
1. Preparation of a montan wax emulsion
A free carboxyl group of montan wax is neutralized or saponified with a basic compound such like an aqueous ammonia solution and is emulsified in high pressure homogenizer.
2. Preparation of an amide wax emulsion
Fine powder of amide wax is emulsified with small amount of surfactant such like polyoxyethylene oleyl ether (nonionic active agent), alkyldiphenyl ether sodium disulphonate (anionic active agent) and a thickener such like xanthane gum in a dispersing vessel at high speed rotation.
3. Preparation of an oxidized polyethylene wax emulsion
An oxidized polyethylene wax is emulsified by using a surfactant such like polyoxyethylene stearyl ether and a basic compound such like a potassium hydroxide in an autoclave at high temperature and high pressure.
Pigment Yellow 180 of the present invention is used for a colorant for a various kind of applications such as printing ink, paint, plastics, rubber, full-color-toner for a copying machine or a printer, color filter for liquid crystal display equipment. It is used particularly preferably for a colorant for transparent resins such as polyester resin, polyvinyl chloride resin, polypropylene resin, polycarbonate resin, acrylic resin, polystyrene resin, styrene-acrylic resin, etc., a yellow colorant for a full-color-toner for a copying machine or a printer, a color filter for liquid crystal display equipment, etc.
Thus this invention relates to printing ink, inkjet ink, paint, plastics, rubber, a full-color-toner for a copying machine or a printer, a color filter for liquid crystal display equipment, as well.
This invention is described below further in details by raising Examples, however this invention is not limited to those Examples.